1. Field of the Invention
The present invention relates to a refrigerant filling apparatus of the refrigerating and air conditioning apparatus and a refrigerant filling method of the refrigerating and air conditioning apparatus.
2. Description of the Related Art
In general, the refrigerating and air conditioning apparatus configuring a refrigeration cycle comprises an indoor unit, an outdoor unit, and connection pipes connecting the indoor unit to the outdoor unit. The indoor unit includes an indoor side heat exchanger. The outdoor unit includes an outdoor side heat exchanger, a compressor, and a pressure reducing solenoid valve. These are connected to the connection pipes at an inside of the outdoor unit. The indoor unit and the outdoor unit configured accordingly are connected by the connection pipes at an installation site to function as the refrigerating and air conditioning apparatus.
There are various environments for installing the refrigerating and air conditioning apparatus. Depending on the installation environments, the connection pipes of various lengths are used. For this reason, an inner capacity of the refrigeration cycle varies depending on the lengths of the connection pipes. Also, an indoor side heat exchanger 3 has a different capacity depending on an indoor unit B. Therefore, refrigeration cycle capacities differ depending on the installation environments.
A refrigerant that circulates through a refrigerant circuit is required for the refrigerating and air conditioning apparatus to function. Since a required refrigerant amount varies for different refrigeration cycle capacities depending on the installation environments, so that it is difficult to fully fill up the required refrigerant amount in advance in the refrigeration cycles.
Patent document 1 discloses a refrigerant filling apparatus for securing a reliability of the refrigeration cycle, and for automatically filling an appropriate and additional refrigerant amount depending on an installation mode of the conventional refrigeration air conditioning apparatus. The refrigerant cycle of the refrigerant filling apparatus has an outdoor unit including a compressor, an outdoor heat exchanger, a pressure reducing apparatus, and a liquid collecting device, and an indoor unit including an indoor side heat exchanger and a pressure reducing apparatus, which are connected by the connection pipes. A main flow unit of a supercooling heat exchanger providing a sub flow unit is disposed in between the liquid collecting device of the indoor unit and the indoor unit. One end of the sub flow unit is connected to a refrigerant cylinder via a refrigerant filling solenoid valve, and the other end is connected to a suction side of the compressor. According to this refrigerant filling apparatus and the refrigerant filling method, opening and closing of the refrigerant filling solenoid valve is controlled, in relation to a supercooling level of the refrigerant at an outlet of the main flow unit.
Patent document 2 discloses a refrigerant filling method and its apparatus, for providing a refrigerant filling method for a refrigeration cycle capable of automatically and appropriately adjusting the refrigerant amount which is additionally filled at a time of installation of the refrigeration cycle. At trial operation after connecting the outdoor side unit and the indoor side unit with the connection pipes, the refrigerant is filled to a refrigerant circulation path while monitoring predetermined operation parameters that regulate a refrigerant pressure and temperature, a superheating level and/or supercooling level(s) of the refrigerant are detected at each point of the refrigerant circulation path, and filling of the refrigerant stops automatically after the superheating level and/or supercooling level have/has reached since an appropriate amount of the refrigerant is filled.
Patent document 3 discloses a filling method of a heat pump apparatus. A refrigerant supplying source is attached to a filling port of the heat pump apparatus. The refrigerant is filled by a predetermined amount in steps while the compressor is in operation. An inlet temperature and outlet temperature of an indoor coil are detected for every filling of a predetermined amount of the refrigerant. A temperature difference of the two temperatures detected is obtained. The temperature difference is compared with a previously obtained temperature difference. Filling stops when a difference of the temperature differences reaches a threshold value as a result of the comparison.                [Patent document 1] Japanese Laid-Open Patent Publication No. 2005-114184        [Patent document 2] Japanese Laid-Open Patent Publication No. 2005-241172        [Patent document 3] Japanese Patent Publication No. HEI 6-21749        